Susceptibility of Phelipanche and Orobanche species to AAL-toxin

• Published in: Planta 2009-10, Vol.230 (5), p.1047-1055
• Main Authors: de Zélicourt, Axel, Montiel, Grégory, Pouvreau, Jean-Bernard, Thoiron, Séverine, Delgrange, Sabine, Simier, Philippe, Delavault, Philippe
• Format: Article
• Language: English
• Subjects: Agriculture; Alternaria; Amino Acid Sequence; Apoptosis; Biochemistry, Molecular Biology; Biodiversity and Ecology; Biological and medical sciences; Biomedical and Life Sciences; Biosynthesis; Botanics; Cell death; Cell Death - drug effects; Ceramides; Cloning, Molecular; DNA Fragmentation - drug effects; Ecology; Environmental Sciences; Forestry; Fundamental and applied biological sciences. Psychology; Fungi; Fusarium; Germination - drug effects; Life Sciences; Molecular Sequence Data; Mycotoxins; Original Article; Orobanchaceae - drug effects; Orobanchaceae - metabolism; Orobanchaceae - microbiology; Orobanche - cytology; Orobanche - drug effects; Orobanche - microbiology; Parasitism; Parasitism and symbiosis; Phytopathology and phytopharmacy; Phytopathology. Animal pests. Plant and forest protection; Plant Diseases - microbiology; Plant physiology and development; Plant Proteins - chemistry; Plant Proteins - metabolism; Plant Sciences; Plants; Seedlings; Seedlings - cytology; Seedlings - drug effects; Seedlings - microbiology; Seeds - metabolism; Sequence Alignment; Sequence Homology, Amino Acid; Species Specificity; Sphingolipids; Sphingosine - toxicity; Toxins; Vegetal Biology; Yeasts
• ISSN: 0032-0935; 1432-2048
• DOI: 10.1007/s00425-009-1008-1

Fusarium and Alternaria spp. are phytopathogenic fungi which are known to be virulent on broomrapes and to produce sphinganine-analog mycotoxins (SAMs). AAL-toxin is a SAM produced by Alternaria alternata which causes the inhibition of sphinganine N-acyltransferase, a key enzyme in sphingolipid biosynthesis, leading to accumulation of sphingoid bases. These long chain bases (LCBs) are determinant in the occurrence of programmed cell death (PCD) in susceptible plants. We showed that broomrapes are sensitive to AAL-toxin, which is not common plant behavior, and that AAL-toxin triggers cell death at the apex of the radicle as well as LCB accumulation and DNA laddering. We also demonstrated that three Lag1 homologs, encoding components of sphinganine N-acyltransferase in yeast, are present in the Orobanche cumana genome and two of them are mutated leading to an enhanced susceptibility to AAL-toxin. We therefore propose a model for the molecular mechanism governing broomrape susceptibility to the fungus Alternaria alternata.